Remove openapi in .csproj since it comes transitively

Author: nicholasdalhaug

api/api.csproj

@@ -45,12 +45,6 @@
     <PackageReference Include="MQTTnet" Version="4.3.7.1207" />
     <PackageReference Include="MQTTnet.Extensions.ManagedClient" Version="4.3.7.1207" />
     <PackageReference Include="Swashbuckle.AspNetCore" Version="10.2.3" />
-    <!--
-      Pin Microsoft.OpenApi to the patched 2.x version (2.7.5) instead of the
-      vulnerable 2.4.1 pulled in transitively by Swashbuckle.AspNetCore
-      (CVE-2026-49451 / GHSA-v5pm-xwqc-g5wc).
-    -->
-    <PackageReference Include="Microsoft.OpenApi" Version="2.7.5" />
     <!--
       Pin SQLitePCLRaw.bundle_e_sqlite3 to the 3.x line so the native SQLite library is
       sourced from SourceGear.sqlite3 (SQLite >= 3.50.4) instead of the deprecated and